If you have any more ideas on how to use the Yubikey, feel free to comment!

Also, If you’re not using 2 factor authentication yet, I urge you to start using it. It gives you a nice additional layer of account security, with limited hassle. It doesn’t even have to cost you any money, if you’re using a software solution. Checkout twofactorauth.org for a (non-comprehensive) list of sites that support it!